The mouse has been a critical component of our program's ability to examine CF questions in an in vivo setting. We have compiled a large list of CF or CF-related mouse models (over 50) and have made them congenic to provide isogentic tools to the research community. This resource has become an international resource, with nearly 60 investigators using the Core (16 local and 38 across the US, Canada, Europe and Australia). We have set up MTAs that are as non-restrictive as we can make them so that CF research is not impeded. We have developed CF models ourselves, most recently conditional (floxed) alleles of Cftr and are currently generating mice carrying human CFTR to allow additional questions to be answered. With the advent of the CF pig and ferret, the mouse models we use also provide the opportunity for comparative studies. As is apparent with all CF animal models to date, the CF mouse is fragile and requires special husbandry, a service most effectively provided by a core. The overall goal of the CF Mouse Models Core is to provide mouse models of CF for understanding the pathophysiology of the disease and for development of therapies. To continue to accomplish our goals, the specific aims of the CF Mouse Models Core are: To provide well-characterized CF mouse models to the institutional, regional, national and international CF research community. Expedite data collection for preliminary studies and facilitate training in experimental procedures involving CF mouse models. We provide many services to CF investigators that include collecting phenotypic data (e.g., weight, length, survival etc.,) and obtaining tissues from CF mouse strains, carrying out lung infection and/or drug dosing experiments as well as training in CF mouse handling and care. These services are utilized daily by institutional users and frequently by external users. To maintain a centralized database that contains breeding history, phenotypes observed and experimental records of the various CF mouse strains in the Core.